Lehrplan; Syllabus; Curriculum research ; Bilingual method ; Instruction (medium of) ; Medium of instruction ; Classroom communication; Instructional communication ; Foreign language teaching policy ; Alternation (biling.) ; Language shift (biling.) ; Sprachwechsel (biling.) ; Sprachenwahl; Language choice; Diglossia ; Bilingual education ; Afrika (port. Sprache in) ; Africa (Portuguese language in) ; Portuguese in Africa ; Tsonga; Xichangana; Changana